Durable connections between guide blading and cover bands therefor are accomplished in many instances by hot or cold riveting. In both cases, the riveting process can be carried out by means of a hammering or rolling operation. It is known to use stationary riveting machines for either procedure, and mobile riveting apparatus can be used for applying the hammering technique.
A high-quality riveted joint can be accomplished by the known radial riveting method, a method that is similar to cold extrusion molding but it requires the use of special machines in view of the special operational requirements. This means that the objects to be riveted together, in the present case, guide blade carrying turbine semi-cylindrical components and their cover bands, must be fed into the radial riveting machine. Since modern, large-sized turbine cylinders cannot be readily moved in this manner, a manual riveting technique is being used in most cases. This manual riveting operation by means of a hammer, and possibly involving also a heating operation, requires great skill, aptitude and experience for accomplishing a properly riveted joint. The expenditure of time, and also the annoying noise level are relatively high in comparison with the mechanical radial riveting method. Furthermore, the riveted joints so produced will be of a diverse quality, and there will always be the danger of hidden deficiencies, such as crack formations, insufficient filling of rivet holes and stresses within the material, especially in the case of hot-riveting.